Egypt's Nile Valley Basin Irrigation

(excerpted from Pillar of Sand)

In striking contrast to the early Indus civilization and those of Sumer, Akkad, Babylonia,
and Assyria in Mesopotamia, the great Egyptian civilization in the Nile River valley has sustained
itself for some 5,000 years without interruption. It lasted through warfare and conquest by the
Persians, Greeks, Romans, Arabs, and Turks, as well as through pandemic disease that devastated its
population. Yet its agricultural foundation remained intact. Only in more recent times has the
sustainabililty of Egyptian agriculture come into question. In response to a 20-fold increase in its
population over the last two centuries-from 3 million in the early 1800s to 66 million today-Egypt
replaced its time-tested agriculture based on the Nile's natural flow rhythms with more intensified
irrigation and flood management that required complete control of the river.[1]

Compared with the flashy floods of the Tigris and the Euphrates, the historic Nile flood was
much more benign, predictable, and timely. As is the case today, most of its flow originated from
monsoon-type rains in the Ethiopian highlands. The remainder came from the upper watershed of the
White Nile around Lake Victoria. With almost calendrical precision, the river began to rise in
southern Egypt in early July, and it reached flood stage in the vicinity of Aswan by mid-August.
The flood then surged northward, getting to the northern end of the valley about four to six week
later.

At its peak, the flood would cover the entire floodplain to a depth of 1.5 meters. The waters
would begin to recede in the south by early October, and by late November most of the valley was drained
dry. Egyptian farmers then had before them well-watered fields that had been naturally fertilized by
the rich silt carried down from Ethiopia's highlands and deposited on the floodplain as the water spread
over it. They planted wheat and other crops just as the mild winter was beginning, and harvested them
in mid-April to early May. By this time, the river's flow had diminished, sustained only by the more
constant flow of the White Nile; the floodplain was completely dry. Then, magically to the ancients,
the cycle started all over again. Even into modern times, every June 17th
Egyptians celebrated the "'Night of the Drop,' when the celestial tear fell and caused the Nile to
rise."[2]

The Egyptians practiced a form of water management called basin irrigation, a productive
adaptation of the natural rise and fall of the river. They constructed a network of earthen banks,
some parallel to the river and some perpendicular to it, that formed basins of various sizes. Regulated
sluices would direct floodwater into a basin, where it would sit for a month or so until the soil was
saturated. Then the remaining water would be drained off to a basin down-gradient or to a nearby canal,
and the farmers of the drained plot would plant their crops.[3]

The earliest evidence of water control in ancient Egypt is the famous historical relief of
the mace head of Scorpion King which dates to around 3,100 BC. It depicts one of the last
predynastic kings, holding a hoe and ceremoniously cutting a ditch in a grid network. Besides
attesting to the importance of these waterworks and the great ceremony attached to them, this
picture confirms that Egyptians began practicing some form of water management for agriculture
about 5,000 years ago.[4]

Egyptian irrigators did not experience many of the vexing problems that plagued (other historic)
irrigation societies. The single season of planting did not overly deplete the soil, and fertility
was naturally restored each year by the return of the silt-laden floodwaters. In some basins,
farmers planted grains and nitrogen-fixing legumes in alternative years, which helped maintain the
soil's productivity. Fallowing land every other year, which was essential in (areas like) Mesopotamia,
was thus unnecessary in the Nile valley.[5]

Neither was salinization a problem. The summer water table remained at least 3-4 meters below
the surface in most basins, and the month or so of inundation prior to planting pushed whatever salts
had accumulated in the upper soil layers down below the root zone. With salt buildup naturally checked
and fertility constantly restored, Egyptian agriculturists enjoyed not only a productive system,
but a sustainable one.

For nearly 1,500 years Egyptian farmers cultivated about 800,000 hectares under this system of
basin irrigation. The shaduf, the water-lifting device already in use in
Mesopotamia appeared in upper Egypt sometime after 1500 BC (see
Illustration 1). This technology
enabled farmers to irrigate crops near the river banks and canals during the dry summer. This would
have allowed the cultivated area to expand by 10-15 percent. A similar increase might have been
afforded by the waterwheel, introduced sometime after 325 BC (see
Photograph 1). So by the time
Egypt had become a breadbasket for the Roman Empire, some 1 million hectares of land were
effectively under cultivation in the course of a year.[6]

Illustration 1. A shaduf was used to raise water above the
level of the Nile.

Photograph 1. A noria, buckets attached to
a waterwheel, was another device used to lift water.

The blessings of the Nile were many, but they did not come without some costs. A low flood
could lead to famine, and too high a flood could destroy dikes and other irrigation works. Even a
2-meter drop in the river's flood level could leave as much as a third of the floodplain
unwatered.[7]

The well-known biblical account of Joseph and the Pharaoh's dream is a reasonable reflection of
the threat of famine that Egyptians periodically faced. Asked to interpret his ruler's dream, Joseph
foretells several years of abundant harvests followed by seven years of shortage, and advises the
Pharaoh to begin storing massive quantities of grain to avert famine. During a period of disappointing
floods between the reigns of Ramses III and Ramses VII in the twelfth century BC, food shortages
caused the price of wheat to rise markedly. Prices stabilized at a high level until the reign of
Ramses X, and then fell rapidly as shortages eased by the end of the Ramessid Dynasty, about 1070
BC.[8]

Because of the link between the Nile's flow level and Egyptian well-being, early on the ancient
Egyptians developed a system for measuring the height of the Nile in various parts of the country.
This monitoring allowed them to compare daily river levels with years past and to predict with some
accuracy the coming year's high mark. At least 20 "nilometers"
were spaced along the river, and the maximum level of each year's flood was recorded in the palace
and temple archives (see Photograph 2).[9]

In combination, the reliability of the Nile flood and the unpredictability of its magnitude
rooted ancient Egyptians deeply in nature and fostered respect for order and stability. Rulers
were viewed as interveners with the gods to help ensure prosperity. Father of all gods was the
god of the Nile-Hapi-who although male was portrayed with breasts to show his capacity to
nurture.[10]

The Egyptians worshipped Hapi not only in temples, but through hymns:

Praise to you, O Nile, that issues from the Earth, and comes to
nourish Egypt . . .

If his flood is low, breath fails, and all people are impoverished; the offerings to the gods
are diminished, and millions of people perish. The whole land is in terror . . .

When he rises, the land is in exultation and everybody is in joy . . .

He fills the storehouses, and makes wide the granaries; he gives things to the
poor.[11]

In contrast to (other historic) civilizations, early Egyptian society did not centrally
manage state irrigation works. Basin irrigation was carried out on a local rather than a national
scale. Despite the existence of many civil and criminal codes in ancient Egypt, no evidence exists
of written water law. Apparently, water management was neither complex nor contentious, and oral
tradition of common law withstood the test of a considerable amount of time.

Although difficult to prove, the local nature of water management, in which decisionmaking
and responsibility lay close to the farmers, was probably a key institutional factor in the overall
sustainability of Egyptian basin irrigation. The many political disruptions at the state level,
which included numerous conquests, did not greatly affect the system's operation or maintenance.
While both slaves and corvee labor were used, the system's construction and
maintenance did not require the vast numbers of laborers that Mesopotamia's irrigation networks
demanded. The waves of plague and warfare that periodically decimated Egypt's population did not
result in the irrigation base falling into serious disrepair, as occurred in (other historic
systems).

Local temples appear to have played an important role in redistributing grain supplies to
help cope with the periodic famines. From very early times, boats plied the Nile and were used
to transport grain from one district to another. The surplus from several districts might be
stored in a central granary and shared to secure food supplies for the whole region. Fekri Hassan,
a professor in the department of Egyptology at the University of London, speculates that the emergence
of kingship in Egypt was linked to the need for larger coordination in collecting grain and providing
relief supplies to districts experiencing crop failure.[12]

The central government imposed a tax on the peasant farmers of about 10-20 percent of their
harvest, but the basic administration of the agricultural system remained local. As Hassam observes,
"Egypt probably survived for so long because production did not depend on a centralized state. The
collapse of government or the turnover of dynasties did little to undermine irrigation and agricultural
production on the local level."[13]

Overall, Egypt's system of basin irrigation proved inherently more stable from an ecological,
political, social, and institutional perspective than that of any other irrigation-based society in
human history. Fundamentally, the system was an enhancement of the natural hydrological patterns of
the Nile River, not a wholesale transformation of them. Although it was not able to guard against
large losses of human life from famine when the Nile flood failed, the system sustained an advanced
civilization through numerous political upheavals and other destabilizing events over some 5,000 years.
No other place on Earth has been in continuous cultivation for so long.

Notes

Early 1800s population from: Malcom Newson, Land, Water, and Development: River
Basin Systems and Their Sustainable Management (London: Routledge, 1992); current
population from Population Reference Bureau, World Population Data Sheet,
wallchart (Washington DC: 1998).